Dental caries starts with plaque formation by cariogenic bacteria of tooth decay adhering to tooth surface. The cariogenic bacteria of tooth decay in the plaques metabolize foods to produce acids. These acids decalcify the tooth enamel by dissolving calcium or phosphorus immediately below the tooth surface, resulting in an incipient enamel caries state. Saliva has the function of remineralizing this demineralized part by the action of calcium or phosphorus contained therein and restoring the tooth. Moreover, a dentifrice for promoting remineralization has been produced, which is formulated with microparticles of a fluoride or of hydroxyapatite which is a calcium phosphate having a crystal structure similar to that of tooth minerals.
However, only the use of saliva or a fluoride or hydroxyapatite dentifrice is insufficient for remineralizing the demineralized part. Moreover, a chewing gum or the like for promoting remineralization has been produced, which is formulated with xylitol and calcium phosphate, or phosphoryl oligosaccharides of calcium. However, the chewing gum or the like formulated with xylitol or various calcium phosphates is insufficient for remineralizing the demineralized part.
Thus, studies have been made to enhance the effect of hydroxyapatite on dental caries, and preparations have been proposed, such as: a dentifrice for an oral cavity which is formulated with hydroxyapatite of 0.05 μm to 1.0 μm in particle size and can enhance repair of minute roughness in tooth surface, tooth surface protection, tooth decay prevention, dentin reinforcement, and whitening effect (see Patent Document 1); a composition for an oral cavity which is formulated with low crystalline hydroxyapatite and can prevent oral diseases or discomfort by adsorbing onto oral bacteria for their eradication (see Patent Document 2); and a 3DS home care agent for eradication of cariogenic bacteria of tooth decay, which is formulated with low crystalline or amorphous hydroxyapatite (see Patent Document 3).
Patent Document 1: Japanese Patent Laid-Open No. 9-202717
Patent Document 2: Japanese Patent Laid-Open No. 2001-122748
Patent Document 3: Japanese Patent Laid-Open No. 2004-35416